Modifying agents are used in polymer production to react (or modify) an active terminal of an unmodified polymer. The agents can be used to terminate a polymerization reaction and thus can be also referred to as terminating agents. An example of a terminating agent used in polymer production is dioctyltin bisoctylmaleate. Dioctyltin bisoctylmaleate is supplied by various companies, and as such, the purity and quality of dioctyltin bisoctylmaleate supplies can vary from supplier to supplier and from batch to batch. The undesirable components or impurities present in dioctyltin bisoctylmaleate can negatively affect polymer production and efficiency. For example, low quality dioctyltin bisoctylmaleate can result in the formation of precipitates during manufacturing that can clog processing equipment and increase polymer processing time and costs. Further, the precipitates, when present, can be undesirably added to polymer reactions and potentially increase impurities or create by products in the final polymer product.
Presence of undesirable components in dioctyltin bisoctylmaleate, such as impurities or by products, can be confirmed by nuclear magnetic resonance (NMR). Although this useful technique can provide a quantitative analysis of dioctyltin bisoctylmaleate, such as in the research and development area, the technique is not as useful for manufacturing quality control (QC) because QC labs are often not equipped with personnel and/or equipment needed to perform NMR analysis. NMR testing requires expensive equipment and can be time consuming. Thus, NMR is not conducive to time-sensitive polymer production operations. There is, however, a need for efficient QC analysis of dioctyltin bisoctylmaleate supplies to determine quality and purity and that has a high degree of quantitative precision and reproducibility. Such methods of QC analysis can improve the quality of the polymers being produced and reduce costs and delays in polymer manufacturing.